NEW YORK — Pretty soon, your phone might remind you to pick up laundry detergent as you peruse the microbrews in the supermarket, just a couple of aisles away.

Mobile shopping startup InMarket started using Apple’s (AAPL) in-store location technology, iBeacon, on Monday to send shoppers deals, rewards and grocery list reminders inside U.S. grocery stores to the 20 million people who use its apps.

IBeacon, which works with Apple devices running iOS 7, is already being used inside Apple stores. In all cases, shoppers will only receive notifications if they download the apps — such as inMarket’s Checkpoints — with the iBeacon feature and opt in to receive them.

As of Monday, InMarket’s “Mobile to Mortar” iBeacon feature is available in dozens of Safeway and Giant Eagle stores in San Francisco, Seattle and Cleveland, but InMarket says the number will grow to more than 150 in the next couple of weeks and thousands of stores, grocery and other types, by the end of 2014.

IBeacon is sometimes called a micro-location technology because it works similar to GPS, but much more precisely. Instead of getting you to an address, it could guide you once you are inside a store. IBeacon transmitters placed around stores use Bluetooth wireless technology to give your phone more precise information about your location. That’s not possible with GPS, which don’t work well indoors and aren’t good at distinguishing between locations that are just a few feet apart.

Researchers said Sunday the mass die-off occurred because unusually large amounts of sea ice forced penguin parents to travel farther in search of food for their young. By the time they returned, only two out of thousands of chicks had survived.